Our research focuses on characterizing in humans the effects of drugs and abuse when taken in combination. We worked on two projects during 1997. First, we completed an experiment examining the effects of acutely administered caffeine on preference between cocaine use versus varying amounts of money. Preference for cocaine decreased significantly as the value of the monetary alternative increased and caffeine did not alter that relationship. These results suggest that caffeine at commonly used doses is not likely to increase relapse among cocaine abusers. Evidence from our treatment clinic are consistent with that conclusion.